The organization says its the most growth in one year since 2005, and its membership is the highest it's been since 2009.

More than 75 percent of other homebuilders associations saw their membership decline in 2012, and only 5 percent saw "substantive growth," the Portland group said.

The Portland area saw a boom in construction activity last year, with permits for single-family homes up 34 percent compared with a year earlier. Permits for apartment and condo construction showed even greater growth.